Trapping of Molecules through Stark Effect

由于电磁场与分子之间的相互作用通常非常弱，传统的激光冷却和俘获技术对分子是无效的。这个研究项目的目标是通过使用静电场或强激光辐射来开发分子的三维捕获。我们的研究成果总结如下：1。从理论上研究了线性极性分子在静态四极电场中的动力学及其碰撞过程。经典分析表明，沿特定方向旋转的分子会受到一个向场分布中心的恢复力，从而被三维捕获。圈闭寿命是根据马约拉纳过渡来制定的。我们还提出了一种用环形电极使分子减速的方法。利用光学偶极子力捕获饱和溶液中析出的小晶体。在过饱和明矾溶液中，机械力影响晶体生长动力学，形成球形多晶。由于作用在析出晶体上的梯度力不同，析出晶体在空间上按大小分布。在远共振光学偶极子力阱中对分子晶体进行了激光烧蚀以产生气态分子。我们的方法的独特之处在于，捕获激光也可以作为烧蚀光源。目前，激光电离和探测被困在CO_2激光束焦点中的分子正在进行中。

The techniques of conventional laser cooling and trapping are not effective for molecules because the interaction between electromagnetic fields and molecules are usually very weak. The goal of this research project is to develop a 3-dimensional trapping for molecules by use of static electric fields or strong laser radiation. Outcomes of our research are summarized as follows.1. We theoretically investigated dynamics of linear polar molecules in static quadrupole electric fields and their collision process. Classical analysis shows that molecules rotating in a specific direction experience a restoring force toward the center of the field distribution, being 3-dimensionally trapped. The trapping lifetime was formulated in terms of the Majorana transition. We also proposed a method of decelerating molecules with a ring electrode.2. The optical dipole force was used to trap small crystals precipitated from saturated solution. It has been demonstrated that the mechanical force influences dynamics of crystal growth in supersaturated alum solution and produces spherical polycrystals. Precipitated crystals are spatially distributed by their size because of the difference in the gradient force acting on them.3. Laser ablation of molecular crystal was carried out to produce gaseous molecules inside a far-off-resonant optical dipole force trap. Our method is unique in that the trapping laser also works as an ablation light source. The laser ionization and detection of molecules trapped in the focus of CO_2 laser beam are now in progress.